This invention relates generally to pipe joints and more particularly to a method and apparatus for forming a pipe joint.
Pipe made of polymericmaterial, such as polyethylene and polyvinylchloride, has numerous applications, such as in culverts, sewers, storm drains and for industrial piping, to name only a few. The use of polymeric pipe is advantageous because of its relatively low cost, light weight, strength and resistance to corrosion. The present invention has particular application to polyethylene pipe which is formed by extrusion to have an inner cylindrical wall, a generally concentric outer cylindrical wall and ribbing located between and connecting the inner and outer walls. The extruded pipe having the aforementioned construction is sometimes referred to in the industry as "profile wall" pipe. Profile wall pipe uses less material and is even lighter in weight than solid pipe made of polymeric material.
Profile wall pipe is extruded in lengths which are sufficiently short to permit transportation and handling. At the site where the pipe is to be installed, the shorter pipes are joined together to form a continuous piece of piping of a desired length. A common way of joining profile wall pipes and other pipes made of polymeric material is to fuse the pipes together. However, a special fusion machine is required to make the joint. The machine may cost $5,000 a day to operate and be able to join only about 200 feet of pipe during the day. Moreover, the joining operation must occur outside the trench where the piping is to be placed, requiring additional labor to move the pipe from the fusion machine to its final resting place.